These are complimentary skills for season assassins. Blood of winter
ice allows for a controlled slowing of the assassin's metabolism
so that he or she moves slower and heals faster. Blood of summer fire
does the opposite and allows an assassin to greatly improve his or her
speed, at the expense of healing slower. Neither one of the affects
may be canceled out by normal magic-user hastes or slows, and only the
assassin may regulate them using his/her skills.
In addition, blood of winter ice gives considerable protection against cold
based attacks, whilst blood of summer fire gives protection against
fire based attacks.